This invention relates to a device for positioning the limbs of a crossbow relative to its riser and, in addition, has applicability to the attachment of the limbs of an archery bow to its handle.
Proper mounting of a bow limb to the riser of a crossbow is of prime importance to the efficient operation of the crossbow. The limbs are typically attached to the riser by a bolt which passes through a hole or slot in the limbs and is received in a threaded bore in the riser. A semicircular depression is formed in the riser which receives a half-round pivot member having its flat side attached to the limb. The underside of the limb does not touch the riser but rather rests on the half-round member about which the limb can pivot. The same type of arrangement is prevalent for mounting limbs to the handle of an archery bow.
There are many problems associated with this mounting arrangement, particularly when the bow is of the compound variety wherein the forces are magnified. Because most limbs are made of fiberglass, any intrusion thereof, such as the hole for the bolt, creates an area of fatigue substantially weakening the limb. Thus, if the half round member is attached to the limb by, for example, a bolt, another hole must be formed in the limb thereby further weakening it. To avoid this second intrusion of the limb, the half-round pivot member, which is usually made of plastic, is often glued to the limb. However, the large shear force created when the crossbow is cocked and when it is fired often causes a loosening of the pivot member.
Additionally, the placement of the pivot member is critical. Any slight misalignment of the pivot member causes the limbs to be misaligned with the riser which can increase the shear force. Thus, care must be taken when manufacturing the crossbows with these types of limb attachments so that the pivot member is properly positioned.
It is thus an object of the present invention to provide a system of positioning the limbs of a crossbow relative to its riser or the limbs of an archery bow relative to its handle.
It is another object of the present invention to provide a system, as above, which does not require any additional intrusions of the limbs, as by a hole or the like, other than the slot or hole required to attach an end of the limb to the riser.
It is a further object of the present invention to provide a system, as above, which will not weaken the limbs and which will permit them to be subjected to the additional forces created by a compound crossbow.
These and other objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed.
In general, a crossbow made in accordance with the present invention includes a riser and at least one longitudinally extending limb having one end attached to the riser. A pocket receives the end of the limb and the pocket and the limb are configured so as to prevent longitudinal movement between the limb and the pocket.
A preferred exemplary system for attaching bow limbs to the riser of a crossbow incorporating the concepts of the present invention is shown by way of example in the accompanying drawings without attempting to show all the various forms and modifications in which the invention might be embodied, the invention being measured by the appended claims and not by the details of the specification.